A side airbag device, as is well known, during a side collision, overturn, or the like of an automobile, inflates a side airbag (hereinafter also simply referred to as airbag) with a gas generator, and receives an occupant's body with this inflated airbag.
It is known to inflate the lower part of a side airbag, with which the waist portion of an occupant comes into contact, to an inner pressure higher than that of the upper part thereof (for example, Japanese Unexamined Patent Application Publication No. 2003-34214, Japanese Unexamined Patent Application Publication No. 2005-238890 and Japanese Unexamined Patent Application Publication No. 11-91493).
It is known to divide the inside of a side airbag into an upper part and a lower part as shown in FIGS. 17 and 18. A side airbag 1A of FIG. 17 is made by sewing the peripheries of an occupant-side panel 2 and a vehicle-body-side panel 3 with sewing thread 4. The inside of the side airbag 1A is divided into an upper chamber 6 and a lower chamber 7 by sewing the middles in the vertical direction of the panels 2 and 3 with sewing thread 5.
A side airbag 18 of FIG. 18 is made by sewing the peripheries of an occupant-side panel 2 and a vehicle-body-side panel 3 with sewing thread 4. The inside of the side airbag 1B is divided into an upper chamber 6 and a lower chamber 7 by providing a partition panel 8 in the middles in the vertical direction of the panels 2 and 3. The partition panel 8 is sewn to the panels 2 and 3 with sewing thread 9.
In the above-described side airbags 1A and 1B, an inflator (not shown in FIGS. 17 and 18) is disposed such that gas from the inflator is supplied first to the lower chamber 7 to start the inflation of the lower chamber 7, and then gas is supplied from the lower chamber 7 to the inside of the upper chamber 6 to inflate the upper chamber 6.
In such conventional side airbags 1A and 1B, during inflation, locally high stress is generated in the vicinities of the sewing threads 5 and 9 of the panels 2, 3, and 8 by the pressure of high temperature and pressure gas acting on them. Thus, it is necessary to reinforce the panels 2, 3, and 8 in the vicinity of the sewing threads 5 and 9 or to provide reinforcing means for enhancing the heat resistance, the manufacture of the side airbags takes time, and the manufacturing cost increases.